Mock Interviewer
Ask Coach
Tap a question to start, or type your own below.
Job Scheduler System Design
Visual Problem Diagram
Scenario
Midnight cron fires 50K jobs at once and your cluster oversubscribes CPUs while a payment reconciliation job waits behind a low-priority email batch. Scheduling, priority, retries, and exactly-once side effects define the interview — and weak answers treat cron like a single-server tab.
Design a distributed job scheduler that runs one-off and recurring tasks across a worker pool with priorities and retries. Cron herds at the top of the hour and non-idempotent retries cause production incidents — your design must address both.
You should support job submit, schedule, execute, retry, cancel, and monitoring. Be ready to explain leases, priority queues, jitter on cron, and idempotency for business side effects.
Constraints
Submit job, cron schedule, priority, execute on workers, retry, cancel, status API
99.9% scheduler availability, at-least-once execution, fair multi-tenant quotas
Millions of jobs per day, 10K workers, peaks at top-of-hour cron
Stages ahead
Log in to start practicing
Preview the problem below. Sign in to start your timed session, save progress, and use the AI coach.